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Chronic smokers often have difficulty breathing because they develop Chronic Obstructive Pulmonary Disorder, or COPD. The two diseases that fall under that category are emphys â¦ ema and chronic bronchitis.
Smoking can cause serious lung problems and can aggravate respiratory infections. It also irritates the mucus membranes and causes the lungs to produce excessive chest mucus. Treat nasal and sinus infections as soon as they occur as these often lead to chest infections or bronchial blockage, and can cause phlegm.